Boys. Point their penis down! Boys may “miss” the absorbent part of the diaper. Commonly this leads to leaks around the waist or belly.
Frequency of diaper changes. Cloth diapers do not hold as much liquid as disposables. They need to be changed every 2-3 hours. If inserts are consistently soaked and causing leaks or more frequent diaper changes, consider adding a booster or changing the inserts for another material (cotton, bamboo, hemp, etc).
Diaper size. Don’t rush into OS diapers (most start to fit best around 10-12 lbs) and be mindful that your child may outgrow NB diapers before the weight recommendations (8-16 lbs).
Relaxed elastics. As diapers wear, the elastics relax (are no longer stretchy). This leads to gaps, particularly when the diaper is compressed in a carseat or when the child moves.
Over stuffing. Many people think that if they add an insert or booster then they can go longer between diaper changes. Unfortunately, over stuffing the diaper keeps it from fitting snugly along the bikini line and leads to leaks.
Compression. This most commonly happens with microfiber inserts. As the child moves and compresses the diaper, they may force the liquid out of the insert. Diaper may also be compressed by carseats, swings, etc. or overly tight clothing.
Wicking. This happens when an absorbent fabric (ex. onesie) touches something wet (leaking diaper). Typically this leads to leaks “up the back” .Check fit, make sure clothing isn’t tucked into the diaper, and let wool breathe.
Age of inserts. Inserts don’t last forever. Depending on their age, wash routine, and usage, inserts and diapers may no longer be able to hold as much liquid as they did when they were new.
Repelling. Improper wash routines (soap scum buildup or mineral buildup), use of fabric softener or diaper creams may lead to the cloth repelling liquids. To test, pour a small amount of water onto the insert and gently apply pressure. If the water beads, the cloth is repelling.
Flooding. If the inserts are saturated in one place, but dry elsewhere, it’s likely getting more liquid than it can distribute. Either the insert is slow-absorbing (bamboo, hemp), a lot of liquid is entering the diaper at once (an older child who has started holding their urine before going at once), or the absorbency is not in the right place (girls: middle of the diaper, boys: front of the diaper, side or belly sleepers: using flats, prefolds or fitteds as they are absorbent “all over”).
Tightness. A diaper that is too tight may also lead to leaks and is also uncomfortable for your little one to wear! Red marks along the leg creases are okay as long as they fad relatively quickly. Think “the red marks left by socks”. Marks that are deep, red/purple, angry looking, and take a long time to fade means the diaper is too tight.
PUL. Check the PUL for cracks and delamination. If the PUL is good, consider that PUL is breathable and thus water-resistant, not waterproof. Leaks through the PUL may mean you need to change the diaper more often (every 2-3 hours) or move/change the absorbency.